This invention relates to a method of manufacturing a semiconductor device which has an interconnection electrode made of a refractory metal or a silicide of the metal.
Generally the metallization material of a semiconductor device is made of aluminum, which has a good workability and which provides a good ohmic contact. The aluminum interconnection electrode, however, is likely to be cut by electromigration. This trouble is more likely to take place if the device has a high packing density and thus its interconnection electrode becomes fine to raise the current density of current flowing in the interconnection electrode. To avoid such trouble, the interconnection electrode may be made of a refractory metal such as molybdenum or a silicide of such a metal.
In manufacturing a semiconductor device, an insulating film is usually formed on an interconnection electrode to protect the wiring or to provide a multi-layer interconnection electrode structure. In most cases the insulating film is a silicon oxide film (including a PSG film and BSG film, each being an oxide layer containing impurities). To form the silicon oxide film on the interconnection electrode, the interconnection electrode is exposed to an oxidizing atmosphere of about 500.degree. C. Thus, if the interconnection electrode is made of molybdenum, the molybdenum electrode will be oxidized during the process of forming a silicon oxide film, and the resultant oxide of molybdenum, which has an extremely high vapor pressure, will be sublimed to sputter and stick onto the constituent elements of the device, thereby deteriorating the electric characteristics of the elements.